SPOILER ALERT: This blog is for people watching the first series of Masters of Sex at UK broadcast pace. Don't read on if you haven't seen episode nine – and if you've seen later episodes, please do not leave spoilers.

'It would be my recommendation that Mrs Johnson try not to take her work so personally and adopts a more detached approach'

Even the absence of Barton and Margaret Scully didn't dent my enthusiasm for this episode, in which a luminous Lizzy Caplan broke my heart several times over. In the first half of the season I felt it was clear that Masters stood for the repressed old world and Virginia the freedom to come. But this episode turned that on its head. What if this isn't a story about how Virginia frees Masters, but rather a story about how Masters entraps Virginia?

Certainly the moving final scene appeared to suggest as much, as Virginia prepared her own reference, remarking that "Mrs Johnson's advantage and disadvantage is that she cares very passionately about everything she does", before concluding that she needs to become "more detached". In other words, more like Masters.

I've discussed before how the show sometimes oversells Virginia, making her almost too perfect, but in this episode they got everything right, from the believably maternal and poised way in which she initially dealt with the medical students to her growing doubts as she first messed up. Virginia is, as Dr DePaul noted, increasingly caught between two worlds. The secretaries clearly no longer see as her one of them, despite Jane's efforts, but her attempts to fit in with her fellow students are doomed because she's already struggling to fit all her commitments into her life.

Meanwhile, the deeply personal nature of her work with Masters only makes the divide more difficult. Her offer to take Jane's place was clearly made for scientific reasons, because she believes in the survey, and to have Masters then clumsily throw that belief back in her face by offering her the money was devastating. Over the past couple of episodes we've seen Virginia begin to truly believe that she could have a scientific career. This episode stripped her of that belief in slow degrees, showing us just how hard it will actually be for her to both get that degree and the respect she deserves.

'You're in that room night after night watching sex, there's no humanity in it … nothing that truly matters in this world can be measured like that'

The show's other great theme is the nature of sex versus the nature of love. Masters would like to reduce everything to science: to say that there's no such thing as desire or passion, that your body simply spasms during orgasm. Libby, on the other hand, sees love as the key: "Without it you're just a man lost in space calling out and hoping to hear something back". Meanwhile, Jane realised that there were lines she was not prepared to cross, and placing her sexual feelings on view to the outside world was one of them, while Vivian learned that not even love can save the day when your betrothed gets the call to stop sleepwalking through life. Most interestingly of all, Essie chose to get a few family secrets out in the open, admitting to her son that she should have spoken up when he was a child and warning him not to make the mistakes his father made. Essie argued that her husband chose the apparent freedom of sex over a chance of family love and this show has gone to some lengths to show us the two ideas in opposition to each other, from Austin's desire to escape his family to Barton and Margaret's empty marriage. And yet, this is also a show obsessed with connection. Every character is desperate to reach out in some way, whether sexually or emotionally. The end of the episode, when Masters sat in darkness watching and rewatching his film of Virginia, surely gave the lie to his own belief that sex is separate from desire. It's not just an involuntary physical response, as the episode's title suggested, but something far more complicated and involved.

Notes and observations

• I find Ethan increasingly interesting. He seems like a real, flawed character capable of doing kind things and bad things and is just as likely to mess up as he is to get it right. I'm also never entirely sure of his motivation. Does he genuinely feel perturbed by his rejection of his father or did he see the chance to break off his engagement with Vivian and seize it? It's not entirely clear. I tend to think that he is confused about his heritage but also a little bit opportunistic at the same time.

• I felt for poor Vivian: She may be silly and naïve and obsessive but her devastation was real. As for Ethan's future – he's already got Masters against him (and it's not yet clear whether Bill has worked out how Libby got pregnant). Now he's added Barton (who has always seemed a pretty adoring dad) to the list.

• It was pretty clever of Libby to use Bill's own lie against him, although I would think that their marriage is heading towards injury time. Does Masters think she had an affair or just went to Ethan for help? It wasn't clear and given the way people like to put on a good face on here, it might not be for some time.

• I'm fascinated by Bill's relationship with his mother. It's almost at Livia and Tony Soprano levels, which is the gold standard for passive-aggressiveness on television. The hospital meal scene with was fantastically awkward, with high points including Essie's opening gambit – "I thought you'd probably worked up an appetite watching all that sex" and Lester's deadpan: "Sometimes I masturbate, not here though."

• In fact, more Lester please. I love Lester. I like to envisage a different future where he and Jane turn Miss Beav St Marie into a Hollywood star.

• Finally, this show does occasionally have issues with subtlety, but having Libby's father leave her for the state of Virginia was a blow too far. Come on show writers, you're better than this, reign it in.

Sexual advice of the week

"Sex has been around for a very long time. It predates even me and every one has done it, except the Virgin Mary." Essie schools Bill in style.

Quote of the week

"This is exactly the problem with religion, you can't joke but you're supposed to believe in magic bushes and floods and three lousy fish saving thousands of dusty, sandy people in the desert." Ethan tries his hand at religious instruction.

So what did you think? Is Masters lying to himself when he reduces sex to science? Can Virginia really stay in the study and is she heading back into Ethan's arms? As always, thoughts and theories below….

Sarah Hughes: Season one bows out with an exceptionally strong double-bill that forced our characters to confront the truth. Cue some more soul-searching, and heartbreaking scenes between Barton and Margaret